JMIR Publications

ABSTRACT

Background:

Sleep disturbances are core symptoms of psychiatric disorders. Although various sleep measures have been developed to assess sleep patterns and quality of sleep, concordance of these measures in patients with psychiatric disorders remains relatively elusive.

Objective:

To examine the degree of agreement among three sleep recording methods and the consistency between subjective and objective sleep measures, with a specific focus on recently developed devices in a population of individuals with psychiatric disorders.

Methods:

We analyzed 62 participants for this cross-sectional study, all having data for polysomnography (PSG), Zmachine, Fitbit, and sleep logs. Participants completed questionnaires on their symptoms and estimated sleep duration the morning after the overnight sleep assessment. The interclass correlation coefficients (ICCs) were calculated to evaluate the consistency between the sleep parameters obtained from each instrument.

Results:

The findings indicated a moderate agreement between PSG and Zmachine for total sleep time (TST: ICC = 0.46, P < .001), wake after sleep onset (WASO: ICC = 0.39, P = .002), and sleep efficiency (SE: ICC = 0.40, P = .006). In contrast, Fitbit demonstrated notable disagreement with PSG (TST: ICC = 0.08, WASO: ICC = 0.18, SE: ICC = 0.10) and exhibited particularly large discrepancies from the sleep logs (TST: ICC = -0.01, WASO: ICC = 0.05, SE: ICC = -0.02). Furthermore, subjective and objective concordance among PSG, Zmachine, and sleep logs appeared to be influenced by the severity of the depressive symptoms and obstructive sleep apnea, while these associations were not observed between the Fitbit and other sleep instruments.

Conclusions:

Present results suggest that Fitbit accuracy is reduced in the presence of comorbid clinical symptoms. Although user-friendly, the Fitbit has limitations that should be considered when assessing sleep in patients with psychiatric disorders.